Methane emissions from beef cattle grazing on semi-natural upland and improved lowland grasslands

• Published in: Animal (Cambridge, England) England), 2015-01, Vol.9 (1), p.130-137
• Main Authors: Richmond, A. S., Wylie, A. R. G., Laidlaw, A. S., Lively, F. O.
• Format: Article
• Language: English
• Subjects: Animal Feed - analysis; Animal Nutritional Physiological Phenomena; animal performance; Animals; beef; beef cattle; biodiversity; Cattle - physiology; Charolais; dairy cattle; Digestion; ecosystem management; ecosystems; Energy Intake; environmental impact; Farming systems and environment; feed intake; Female; finishing; grasses; Grassland; grasslands; grazing; greenhouse gas emissions; heifers; highlands; Holstein; Male; methane; Methane - metabolism; methane production; nutritive value; pastures; Research Article; Seasons; steers; stocking rate; sulfur hexafluoride; sulphur hexafluoride
• ISSN: 1751-7311; 1751-732X; 1751-732X
• DOI: 10.1017/S1751731114002067

In ruminants, methane (CH4) is a by-product of digestion and contributes significantly to the greenhouse gas emissions attributed to agriculture. Grazed grass is a relatively cheap and nutritious feed but herbage species and nutritional quality vary between pastures, with management, land type and season all potentially impacting on animal performance and CH4 production. The objective of this study was to evaluate performance and compare CH4 emissions from cattle of dairy and beef origin grazing two grassland ecosystems: lowland improved grassland (LG) and upland semi-natural grassland (UG). Forty-eight spring-born beef cattle (24 Holstein–Friesian steers, 14 Charolais crossbred steers and 10 Charolais crossbred heifers of 407 (s.d. 29), 469 (s.d. 36) and 422 (s.d. 50) kg BW, respectively), were distributed across two balanced groups that grazed the UG and LG sites from 1 June to 29 September at stocking rates (number of animals per hectare) of 1.4 and 6.7, respectively. Methane emissions and feed dry matter (DM) intake were estimated by the SF6 tracer and n-alkane techniques, respectively, and BW was recorded across three experimental periods that reflected the progression of the grazing season. Overall, cattle grazed on UG had significantly lower (P0.05) in CH4 emissions per unit of feed intake when expressed either on a DM basis (20.7 and 21.6 g CH4 per kg DM intake for UG and LG, respectively) or as a percentage of the gross energy intake (6.0% v. 6.5% for UG and LG, respectively). However, cattle grazing UG had significantly (P